There are many ways of forming an image. For example, images can be formed through thermal transfer of dyes, inkjet applications, electrophotographic reproduction, and silver halide image development.
To form any printed image, the image can be chemically developed from film, or developed from an electronic signal generated from a digital capture device or by scanning a film. For thermal, inkjet, and electrophotographic printing, electronic signals indicating appropriate colors are used to produce cyan, magenta, yellow, and black color signals. These signals are then transmitted to a printer where colored material is transferred to an appropriate receiver element. A color hard copy is thus obtained that corresponds to the original image.
Thermal transfer prints are susceptible to re-transfer of colorants to adjacent surfaces, to discoloration by fingerprints because the colorants remain at the surface of the receiver element, and to scratches during imaging and handling. Heat can be used to drive the colorants deeper into the receiver element. Application of a transparent protective overcoat onto these types of color images is also known, and effectively reduces these problems. The transparent protective overcoat can also provide improved light stability if a UV absorbing compound is incorporated in the formulation.
A clear protective layer can be transferred onto a dye image to give the desired protection and finish. This transparent protective layer can be provided as the sole transferrable material in a thermal transfer donor element, or it can be provided as multiple patches, with or without separate patches containing protective layer that has optimal flash and donor receiver separation during printing and handling of the thermal transfer donor element and the final image print as the protective layer is used to cover the thermal dye images.
The thermal transferable protective laminates currently being used in various thermal products comprise a transparent polymeric layer on a support, which transparent polymeric layer is composed of various components designed to provide needed properties and to solve various problems. One problem encountered with thermal donor elements is known as “flash” in which the protective transparent film to be transferred prematurely separates from the donor ribbon (support), resulting in irregular edges and faults in the resulting thermal dye images. It has been found that this problem can be reduced or eliminated by incorporating particulate materials such as colloidal silica into the protective transparent film.
However, this component is a very expensive material compared to other components of the protective transparent film, for example, polymer or resin binders. Thus, there is a need to find a partial or total replacement of the expensive colloidal silica without experiencing the “flash” problem. The present invention is intended to address this problem.